The present invention relates to an ink liquid supply system in an ink jet system printer of the charge amplitude controlling type.
Generally, the ink jet system printer of the charge amplitude controlling type uses water-color ink. Therefore, if the ambient temperature drops below -5.degree. C. while the ink jet system printer is not used or while the ink jet system printer is transported from an office to another one, the water-color ink may freeze. The freezing of the water-color ink provides the expansion of the water-color ink disposed in the ink liquid supply system to explode the ink liquid supply system.
To prevent freezing of the water-color ink, in the conventional system, antifreezing fluid is mixed with the pressurized water-color ink in, for example, a pressurizing pump. However, any effective methods have not been found to prevent the freezing of the atmospheric pressure water-color ink.
Accordingly, an object of the present invention is to provide an ink liquid supply system in an ink jet system printer of the charge amplitude controlling type, which prevents the explosion of the ink liquid supply system even when the water-color ink at atmospheric pressure freezes.
Another object of the present invention is to provide a novel atmospheric pressure chamber disposed in an ink liquid supply system of an ink jet system printer, which ensures stable operation of the ink jet system printer.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, an atmospheric pressure chamber is disposed between an ink tank and a pressurizing pump. An air buffer surrounded by a resilient wall and communicating with the atmosphere is disposed in the atmospheric pressure chamber so at to contact the water-color ink at atmospheric pressure filled in the atmospheric pressure chamber. When the water-color ink at atmospheric pressure freezes, the expansion of the ink liquid is absorbed by the air buffer, whereby the explosion of the ink liquid supply system is prevented.